Add mpl-2.0 rule from libeigen

Reference: #4015
Reported-by: @alexzurbonsen
Signed-off-by: Ayan Sinha Mahapatra <ayansmahapatra@gmail.com>

Author: AyanSinhaMahapatra

src/licensedcode/data/rules/mpl-2.0_145.RULE

@@ -0,0 +1,8 @@
+---
+license_expression: mpl-2.0
+is_license_notice: yes
+---
+
+has executed a license with Google LLC
+to permit distribution of this code and derivative works as part of Eigen under
+the {{Mozilla Public License v. 2.0}}, as stated at the top of this file.